Complete Glossary of Peptide Terms (2026 Reference)

Last updated: May 18, 2026

Fundamental chemistry

• Amino acid: Organic compound with amino (-NH2) and carboxyl (-COOH) groups; 20 standard amino acids form proteins
• Peptide bond: Amide linkage formed when carboxyl group of one amino acid reacts with amino group of another, releasing water
• Peptide: Short chain of 2-50 amino acids
• Protein: Longer chain (50+ amino acids), typically with secondary, tertiary, and quaternary folding
• SPPS: Solid-Phase Peptide Synthesis — standard manufacturing technique developed by Merrifield (Nobel 1984)
• LPPS: Liquid-Phase Peptide Synthesis — alternative manufacturing for some peptides

Pharmacology terms

• Half-life (t½): Time for plasma concentration to fall by 50%
• Bioavailability: Fraction of administered dose reaching systemic circulation
• AUC: Area Under Curve — total drug exposure over time
• Cmax: Maximum plasma concentration
• Tmax: Time to maximum plasma concentration
• Agonist: Activates a receptor
• Antagonist: Blocks a receptor
• Partial agonist: Activates receptor with submaximal effect

Peptide classes

• GHRH: Growth Hormone-Releasing Hormone — endogenous 44-amino-acid peptide stimulating GH release
• GHRP: Growth Hormone-Releasing Peptide — synthetic ghrelin receptor agonists (ipamorelin, GHRP-2, GHRP-6, hexarelin)
• GHS: Growth Hormone Secretagogue — umbrella term for any compound stimulating GH release
• GLP-1: Glucagon-Like Peptide-1 — incretin hormone with multiple actions
• GIP: Glucose-dependent Insulinotropic Polypeptide — second major incretin
• GnRH: Gonadotropin-Releasing Hormone — controls reproductive hormones
• SST: Somatostatin — inhibits GH and other hormones
• α-MSH: Alpha-Melanocyte-Stimulating Hormone — pigmentation regulator (and PT-141 / melanotan parent peptide)

Receptor abbreviations

• GHRH-R: GHRH receptor on pituitary somatotrophs
• GHS-R1a: Ghrelin receptor — target of GHRPs
• GLP-1R: GLP-1 receptor
• MC1R, MC2R, MC3R, MC4R, MC5R: Melanocortin receptors (1-5)
• IGF-1R: Insulin-like Growth Factor 1 receptor

Specific molecules

• IGF-1: Insulin-like Growth Factor 1 — downstream mediator of GH effects
• IGF-1 LR3: Long-acting IGF-1 analog with R3 substitution
• MGF: Mechano Growth Factor — IGF-1Ec splice variant
• DAC: Drug Affinity Complex — albumin-binding modification (in CJC-1295 DAC variant)
• SNAC: Sodium N-(8-(2-hydroxybenzoyl)amino)caprylate — absorption enhancer in oral semaglutide

Regulatory terms

• NDA: New Drug Application — submission to FDA for approval
• BLA: Biologics License Application
• EUA: Emergency Use Authorization
• RUO: Research Use Only — labeling for non-medical research products
• cGMP: current Good Manufacturing Practice — FDA quality standard
• WADA: World Anti-Doping Agency — anti-doping authority for competitive sport
• TGA: Therapeutic Goods Administration (Australia)
• EMA: European Medicines Agency

Dosing terms

• mcg / μg: Microgram (1/1000 of a milligram)
• BAC water: Bacteriostatic water (sterile water with 0.9% benzyl alcohol preservative)
• Lyophilized: Freeze-dried (the state of most shipped peptides)
• Reconstitution: Adding solvent to lyophilized powder to produce solution
• Insulin syringe: Small syringe with units scale (1 mL = 100 units)
• SC, SQ: Subcutaneous (under the skin) — standard injection route
• IM: Intramuscular
• IV: Intravenous
• IN: Intranasal

Quality and analytical

• COA: Certificate of Analysis
• HPLC: High-Performance Liquid Chromatography — purity testing
• MS / LC-MS: Mass Spectrometry — identity verification
• Purity: Typically reported as percentage by HPLC area
• Salt form: Most peptides are acetate or TFA salts; affects active mass per labeled mg